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They had been inseparable as young children, even with Katsuki’s volatile temper. It was a near perfect match. Deku was happy and sweet like his mother and Katsuki was explosive and loud like his. But they worked, and during sleepovers, they’d watch All Might movies, Deku’s small chubby hand in his. And it felt right. Katsuki knew he was bad with feelings, but this had been almost seventeen years in the making. Soulmates, he’d call them if he was fucking sappy, but he wasn’t. It was good though. It was definitely good.
And then he developed a quirk and Deku didn’t.
He couldn’t explain to you the change that occurred, all the pain and misery he put Deku through. Well, he could, but he won’t. That’s in the past and Deku forgave him.
And the nerd made it into UA. Despite everything, he fucking did it. And he did it with a new, shiny quirk that shattered all his bones and left him in the hospital more times than Katsuki could count. Even with all those casts, he was smiling, green eyes alight with happiness.
They weren’t friends. The wounds were too raw. Katsuki was still bitter and confused, and Deku was still tentative, no matter how the nerd tried to hide it. Something was broken, perhaps irreparably and Katsuki knew it was his fault. He made no moves to repair it at first, and that was his greatest mistake.
Deku still looked at him with stars in his green eyes, no matter how dim they had become. He still thought Katsuki would be the greatest hero and he still called him “Kacchan.” So it was okay. Or at least Katsuki thought.
They had their own friend groups. He had Kirishima. Deku had Round Cheeks and the half-and-half bastard and the others. And it was okay.
They fought and that was the first time Katsuki truly felt the rift between them. Deku wasn’t a quirkless loser anymore. He was good, and maybe one day he’d even be better than Katsuki. If he could figure out how to stop breaking every fucking bone in his body. And that realization hurt, but it was necessary; a harsh reality check.
There was a chasm between them. They were no longer little baby Kacchan and Deku anymore. They were no longer the sweet child reaching his hand out to help as his friend spiraled. They were no longer the cruel middle school bully and the helpless victim. They weren’t even the future number one hero and his biggest supporter.
They were equals.
That revelation finally pushed him over the edge. He didn’t like the space and unspoken words between. He wanted it fixed. But he didn’t make an effort their first year.
Then 1-A became 2-A and it wasn’t good, but it was better. They could hold a conversation now (even if Katsuki yelled through most of it). He was the only one who knew Deku’s secret, and in a way that mattered more than how close Deku was with his friends.
It was at this point that Katsuki believed it could get better. Deku was still his biggest supporter and, though he’d never admit it, Katsuki was his. He only had All Might’s quirk for one year, but he was progressing in leaps and bounds. He only broke minimal bones now, and it was nice to see. It was nice to see the nerd happy.
That’s not when it started, but that’s when Katsuki realized.
He was in love with Deku.
But feelings were stupid (he was scared), so he kept quiet. Avoidance is a good way to forget something (it isn’t), and Katsuki ran from the feelings. He hid them under characteristic anger and insults. He was so adamant on burying his feelings that he never realized the cracks forming in the glass bridge built over the chasm between him and Deku.
It didn’t matter anyway, did it?
They’d always be Kacchan and Deku.
Then the war came and that glass bridge shattered.
Katsuki watched as one quirk became seven became none. And they were right back at square one. But they weren't, were they? Deku was a hero and it didn’t matter anymore that he didn’t have a quirk because Katsuki apologized and they were going to be okay.
But they weren’t.
Kacchan and Deku became Katsuki and Izuku. And that’s a good thing, is it not? It should’ve been. But it felt like erasing their childhood, despite all the bad parts. The look in Izuku’s eyes, however, when Katsuki called him by name was enough to soothe those fears.
Who cares if Izuku didn’t have a quirk? Katsuki would support him and they’d be the strongest. Together. The war was over and Katsuki was still in love. Feelings, it seems, don’t just leave if they’re years in the making. How fucking aggravating. But now Katsuki had a chance. They’d be Deku and Dynamight (they wouldn’t).
And just maybe they could be more (they never would be.)
After all, they were soulmates (in every universe). He wasn’t afraid to believe it now, no matter how sappy it seems. Fate had brought them together and kept them that way through everything. So Katsuki would build him a suit, however much it cost, and they’d open a hero agency, and they’d be Number 1 and Number 2.
Or, at least they should’ve been.
You see, the issue with feelings is that there is always another person. Katsuki loves Izuku. He’d fucking die for him. He wants to hold Izuku’s hand and kiss his forehead, and his cheek, and his nose, and his lips and all the other gross shit couples do. He loves Izuku like his father loves his mother. But in all the time he ran from his feelings, he never realized he was running from Izuku’s as well.
He’d never tell this to anyone, but he was a fan of romantic movies. Funny, angsty, sweet? He didn’t give a fuck. He’d watch them all in the comfort of his room (so his shithead friends couldn’t make fun of him, but he’s sure they know at this point anyway). But no one ever tells you what happens when the movie’s over.
Not all love is forever, after all.
As Katsuki’s feelings grew, Izuku’s dimmed. One fell in love too soon, and the other too late. Being “soulmates” doesn’t mean shit if they were doomed from the start. Or maybe they weren’t. Maybe this is truly all Katsuki’s fault.
So here Katsuki sits, Number 15 on the charts, watching Izuku as Izuku watches Uraraka walk down the aisle. His beautiful green eyes glisten with tears and Katsuki’s red ones do too.
For completely different reasons.
Uraraka is beautiful. She’s strong and kind and one of the only heroes Katsuki truly respects. Both Izuku and Uraraka’s faces glow with happiness, as all their friends sniffle in the crowd. Their vows are sweet and there’s so much love in the green eyes Katsuki has been running after his entire life.
He’s happy for them. He is. But it feels like he’s being torn apart from the inside as he gives his best man speech. He holds back bile when he watches Izuku and Uraraka, his new wife, dance. And he cries alone in his room later that night after everything is over.
Izuku deserves the world. Katsuki just wasn’t it.
It should’ve been him. It could’ve been him.
But it wasn’t.
In the end, there is no Deku and Kacchan. There’s Izuku and Uraraka. And there’s Katsuki. He’ll never be Number 1. He’ll never be partners with Izuku. He’ll never have Izuku’s heart.
And when he finally manages to fall asleep, he dreams of green eyes.
He’ll always be chasing them, but he’ll never catch up.